Belt fed automatic firearms, a.k.a. “machine guns” have been in the military arsenal for over 100 years. For sheer volume of ammunition, a belt fed weapon system is usually the best option. Ammunition belts consist of a long string of cartridges fastened together with pieces of canvas or, more often, attached by small metal links. Guns that use this sort of ammunition typically have a feed mechanism driven by the recoil motion of the bolt.
FIGS. 1A-1D illustrate an example of a belt feeding system 20 for a machine gun 10. FIGS. 1 A and 1B illustrate the machine gun 10 with a bolt 1 cocked back, FIGS. 1C and 1D illustrate the system as it is loading a cartridge 14 into the chamber. FIGS. 1A and 1C are top plan views, with a belt of cartridges 12 being fed from left to right. FIGS. 1B and 1D are side profile views and for FIGS. 1A-1D, the cartridges 14 and belt links 3 are being ejected out of the page.
The machine gun 10 has a bolt 1, and in this example, has a small cam roller 5 disposed on top. As the bolt 1 moves, the cam roller 5 slides back and forth in a long, grooved feed cam piece 2. When the cam roller 5 slides forward, it pushes the feed cam 2 to the right (as illustrated) against a return spring 6. When the cam roller 5 slides backward, the spring 6 pushes the feed cam 2 back to the left. A feed cam lever 7 is attached to a spring-loaded pawl 8 having a curved gripper (not illustrated) that rests on top of the ammunition belt 12. As the cam 2 and the lever 7 move, the pawl 8 moves out, grabs onto a cartridge 14 and pulls the belt 12 through the gun 10. When the bolt 1 moves forward, it pushes the next cartridge 14 into the chamber 16.
The feed system 20 drives the ammunition belt 12 through cartridge guides 9 just above the breech. As the bolt 1 slides forward, the top of it pushes on the next cartridge 14 in line. This drives the cartridge 14 out of the belt 12, against the chambering ramp 11. The chambering ramp forces the cartridge 14 down in front of the bolt 1. The bolt 1 has a small extractor 15, which grips a base of the cartridge 14 when the cartridge 14 slides into place. As the cartridge 14 slides in front of the bolt 1, it depresses the spring-loaded ejector 18.
When a firing pin 19 hits a primer, the powder inside the cartridge 14 ignites and propels the bullet down the barrel 4, the explosive force drives the operating rod 17 and attached bolt 1 backward. When the cartridge shell clears the chamber wall, the ejector 18 springs forward, popping the shell out of the gun through an ejection port. This system lets you fire continuously without reloading.
In the example of the system 20 above, the ammunition must be linked in order to feed correctly. These links 3 add to the overall weight a soldier, or her vehicle, has to bear when in the field. The links 30, 32, 34, 36, as illustrated in FIGS. 2A-2D, are currently made of metal, typically nickel. FIG. 2A illustrates the current U.S. military M27 link for 5.56 mm ammunition. The M27 link is a reduced size of the M13 link for 7.62 mm ammunition. A portion of the link fits into the extractor groove on the cartridge case. The U.S. Navy uses the link with the M63 Stoner Machine Gun. The U.S. Army uses the link with the M249 Machine Gun.
A typical link is two sided, typically a two piece side and a one piece side. A single cartridge is typically inserted into each of the sides of the link. The cartridge is secured into the link by crimping the link closed onto the cartridge. This is typically not done by the manufacturer of the cartridges, but manually in the field in single or 10 round groups. This is a very time consuming process. When the cartridge is forced out of the link as the bolt moves forward, the metal pieces are spread to allow the cartridge to enter the chamber. The link is then expelled from the same ejection port as the spent cartridge.
A goal of the present invention is to form lighter weight links and to pre-link the cartridges during manufacturing.